On Saturday, two car bombs exploded in the Turkish city of Reyhanli, on the Syrian border, killing at least 46 people and injuring 155, while damaging 735 businesses and 120 apartments. No organization has yet claimed responsibility for the bombing.

In the wake of the bombings, Turkish officials pushed Washington to escalate its ongoing intervention to remove the regime of Bashar al-Assad. Turkish Prime Minister Recep Tayyip Erdogan threatened, “Those who target Turkey will be held to account sooner or later … Great states retaliate more powerfully, but when the time is right.”

Over the past week, Erdogan has demanded greater US-NATO efforts to topple Assad, cynically claiming that Obama’s “red line” on chemical weapons use has already been crossed by Assad. This stands in direct contradiction to last week’s revelations by UN investigator Carla del Ponte, who said that UN interviews with survivors of a chemical weapons attack showed that the poison gas was used by the US-backed opposition. She said there was no evidence of chemical weapons use by the Syrian government.

Tough Al Qaeda-linked elements in the US- and Turkish-backed opposition forces have carried out hundreds of such terror bombings in neighboring Syria, the Turkish regime immediately placed the blame squarely on Assad. Turkish Interior Minister Muammer Guler asserted that the bombings were carried out by elements “closely linked with pro-regime groups in Syria.” He cited a Turkish Alawite organization, Acilciler, which has been active in Turkey since the 1970s and was allegedly set up by Syrian intelligence, as a suspect in the bombing.

Speaking in Berlin, Turkish Foreign Minister Ahmet Davutoglu declared: “It is time for the international community to act together against this regime.”

Refuting the Turkish charges against the Syrian government, Syrian information minister Omran al-Zoubi said Syria “did not commit and would never commit such an act, because our values would not allow that.”

Zoubi also denounced Turkey’s decision to give arms and safe passage to terrorist opposition forces backed by the US, Europe, and the Persian Gulf states. Turkey has been a crucial support of the US proxy war in Syria, providing bases for staging and logistical support to the opposition’s offensives and terror bombings in nearby northern Syria.

“They [the Turkish regime] turned houses of civilian Turks, their farms, their property into a centre and passageway for terrorist groups from all over the world,” Zoubi said. “They facilitated and still are the passage of weapons and explosives and money and murderers to Syria.”

Zoubi said that Erdogan should “step down as a killer and a butcher.”

Western press outlets cited fears of clashes between Turkish residents and Syrian refugees around Reyhanli, as the sectarian civil war in Syria and the flood of Syrians fleeing the war fuel ethnic and sectarian tensions in Turkey. More than 300,000 Syrians have taken refuge across the Turkish border.

At least 4.25 million Syrians have been displaced by the war, and more than 80,000 killed. Cities have been pillaged, factories looted, and the economy is collapsing amid a raging civil war stoked by US imperialism. The Al Qaeda-affiliated Al Nusra Front, one of the key elements of the US-backed opposition, has carried out hundreds of terror bombings in Syria.

Protests erupted in Reyhanli against the Turkish government’s participation in the US-led war against Syria, with marchers chanting, “Erdogan murderer!”

“The prime minister brought this on to us,” said a business owner, who asked to be identified only by his first name, Mehmet. “We have no peace anymore. The Syrians are coming in and out, and we don’t know if they are bringing in explosives, taking out arms.”

These protests underscore that the Turkish and US governments are moving to escalate the war in defiance of public opinion. Polls show 62 percent of Americans and 68 percent of Turks oppose the war in Syria.

As popular opposition to war mounts in the working class, the Erdogan regime is intervening aggressively to press for quicker action by Washington, where a debate is raging over how to pursue the Syrian war and broader US imperialist intervention in the Middle East. Former US Secretary of Defense Robert Gates recently warned that increased US intervention in Syria would be a “mistake,” in opposition to the chorus of voices within the ruling class calling for air strikes and “boots on the ground.”

Appearing on ABC’s “This Week,” Senator John McCain blasted what he called the reluctance of the Joint Chiefs of Staff to intervene in Syria, claiming that Israeli airstrikes have proven the weakness of Syria’s air defenses. McCain called for the imposition of a “no-fly zone” over Syria.

There are also reports that sections of the American military and intelligence bureaucracies are considering double-crossing Al Qaeda-affiliated forces in Syria, such as the Al Nusra Front, which have until now served as the US-backed opposition’s shock troops.

A leader of a US-backed opposition militia inside Turkey told the UAE’s The National that US officials were considering mounting drone strikes inside Syria to massacre Al Nusra forces. He cited the US officials as saying, “I’m not going to lie to you. We’d prefer you fight Al Nusra now, and then fight Assad’s army. You should kill these Nusra people. We’ll do it if you don’t.”

This debate is intensified by the manifest failure of the US-backed opposition militias, who have very limited popular support, to topple the Assad regime, despite all the assistance they have received from US imperialism and its allies. With forces of the Lebanese Shiite militia Hezbollah now intervening to support Assad, there is a risk that the US-backed opposition could suffer a catastrophic defeat. There are also reports that Assad could receive further military support from Iran and Russia.

After more than two years of civil war, fomented by the US and its allies, the crisis in Syria appears to be coming to a head. Amid a vast crisis threatening a devastating regional war, the American ruling class is threatening to respond with yet more military violence.

In a recent Washington Post op-ed, Anne-Marie Slaughter—a Princeton professor who is a leading proponent of “humanitarian intervention” and Obama’s chief policy planner at the State Department from 2009 to 2011—wrote that “US credibility is on the line.” From the standpoint of such forces in the US foreign policy establishment, the failure to topple Assad, who has Russian and Chinese backing, would be an unacceptable blow to US efforts to establish its global geo-strategic dominance.

“It comes down to an existential struggle,” said Salman Shaikh of the Brookings Doha center think-tank. “Those who oppose Assad really have to show that they mean it now.”